Endeavour is an impact crater located in the Meridiani Planum extraterrestrial plain within the Margaritifer Sinus quadrangle (MC-19) region of the planet Mars. Endeavour is about 22 kilometers (14 mi) in diameter.[1] Using Mars Reconnaissance Orbiter data, phyllosilicate-bearing outcrops have been detected along the rim of this crater. These minerals may have formed under wet conditions in a low-acidic environment during the early history of Mars.[5] There are raised rim segments to the north, east, and southwest. The rim has become worn, rounded and degraded, with infilling of plains material in a manner similar to the Victoria crater.[6]

When compared to the surrounding plains, the crater floor shows an enhanced spectral signature of basalt and hematite.[7] The interior contains two groups of dune fields. Images taken since 2008 show evidence of changes in some of the associated formations, which may be evidence of active erosion by the martian wind over a period of two to three years.[6] The plains surrounding the rim show evidence of polyhydrated sulfate.[7]

In December 2011, Opportunity rover discovered a vein of gypsum sticking out of the soil along the rim of Endeavour crater. Tests confirmed that it contained calcium, sulfur, and water. The mineral gypsum is the best match for the data. It likely formed from mineral-rich water moving through a crack in the rock. The vein, called "Homestake," is in Mars' Meridiani plain. It could have been produced in conditions more neutral than the harshly acidic conditions indicated by the other sulfate deposits; hence this environment may have been more hospitable for a large variety of living organisms. Homestake is in a zone where the sulfate-rich sedimentary bedrock of the plains meets older, volcanic bedrock exposed at the rim of Endeavour crater.[10]

Endeavour crater averages about 200 to 300 meters deep, with an area in its southeast that goes down to 500 meters deep, according to publication called Degradation of Endeavour Crater, Mars by the Smithsonian Institution.[11] The south-west depression goes down to an elevation of minus 1980 meters, the horse-shoe shaped depression sits in the south-east quadrant and is around minus 1800 to 1900 meters elevation, which is about 400 meters below the surrounding plains.[11] It is noted that the crater has under-gone various erosion processes, with wind being one cause.[11]

The International Astronomical Union named the crater after a town in Canada.[3] The name was approved on 20 October 2008.[12] Due to rules for naming craters, it is officially named after the Canadian town, but the reason this name was proposed was because rover team was using informal nicknames based on a voyage of the HMS Endeavour.[4]

The crater is understood by the 2010s to have two main rock types, the Shoemaker Formation and the Matijevic Formation.[15] It has been classified as a complex crater and it is thought to be so old many of its features have been worn away.[15] Some questions were raised about the tilt of the rim, however understanding is hampered by a lack of knowledge about Martian impact craters: Endeavour was the largest Martian impact crater up to that time to be studied that closely.[15] An example of the difficulty of studying Mars features is also apparent with Orcus Patera, which has various volcanic, tectonic, or cratering events explanations for its formation.[16] One famous Mars realization was that what was then called Nix Olympica was a volcano, and then renamed Olympus Mons thanks to Mariner 9 orbiter observations in the early 1970s.[17] Endeavour crater was identified as having clay minerals, as detected from orbit by Mars Reconnaissance Orbiter, which according to theories at that time indicated rock from an older, wetter, time period on Mars.[18] This type of rock is different from what prevails in other areas of surrounding plains.[18]

What is expected to be a fluid-carved gully was identified at Endeavour crater, probably water.[19] This gully is targeted for exploration by the MER-B rover mission as of October 2016.[19] It reached the gully in 2017 and it was named Perseverance Valley

Colored for minerals. Opportunity traverse is dated to 2010 while it was still on its way to Endeavour. The coloring is based on geological information as observed by the Mars Reconnaissance OrbiterCRISM instrument

Explored in by the MER-B rover, several locations including the Spirit of Saint Lois Crater with Lindberg Mound, Marathon Valley, Lewis and Clark pass, and Spirit mound among other features on or very near the Western rim

HiRise image from MRO, was laid over 3-D topographic map of the terrain, with 5-fold vertical exaggeration; view looking west on to Perseverance Valley on the western rim of Endeavour crater (February 15, 2018 )[32]

MER-B has had such new discoveries at the crater, that that the rover team compared Endeavour to the equivalent of a second landing site for Opportunity.[34][35] For example On sol 2692 (August 22, 2011) the rover began examining Tisdale 2, a large ejecta block. "This is different from any rock ever seen on Mars," said Steve Squyres, principal investigator for Opportunity at Cornell University in Ithaca, New York. [34]

Opportunity's traverse up to March 2015 from its landing site to Endeavour crater. It has traversed south along the Western rim and orbiting spacecraft have help collect data on the rim, which in turn allows the rover to more closely investigate

Self-portrait of Opportunity near Endeavour Crater on the surface of Mars (January 6, 2014).

On March 7, 2009 (sol 1,820), Opportunity first imaged the rim of Endeavour after driving about 3.2 kilometers (2.0 mi) since it left Victoria in August 2008.[8][40]Opportunity also imaged Iazu crater, which is about 38 kilometers (24 mi) away and about 7 kilometers (4.3 mi) in diameter.[40] At that time, Opportunity was 12 kilometers (7.5 mi) from Endeavour as the Martian crow flies, but to avoid hazards, it was estimated that it would take about 30% more driving distance than that to reach Endeavour.[8] Based on the amount of time it had taken to drive from Victoria, it was estimated that this journey would take over one Martian year (23 months).[8] On May 5, 2010, to avoid hazardous dune fields along the direct path between Victoria and Endeavour, the charted route between the two craters was extended to an estimated 19 kilometers.[41]

On September 8, 2010, it was announced that Opportunity had reached the halfway point of the 19-kilometer journey between Victoria crater and Endeavour crater.[42] By June 28, 2011, Opportunity was just under 2 kilometres (1.2 mi) from landfall at the rim of Endeavour crater.[43]

On August 4, 2011, Opportunity was only 120 metres (390 ft) from the rim of Endeavour,[44] and on August 9, 2011 Opportunity arrived at the west rim near Spirit Point to study outcrops never seen before.[9]

MER-B on Sol 2239 imaged the then distant crater rim. On this map several locations of Endeavor are identified including: Cape Tribulation, Cape Bryon, Cape Dromedary, Point Hicks, Torres Strait, and Batavia. Further south the nearby crater Iazu is also marked.

Here is the view from the rover's perspective from that location noted in the above top-down view. The white lines indicate the rover's field of view

MER-B eventually reached Cape Tribulation, and took a panorama from its top: Opportunity's view from Cape Tribulation on the rim of Endeavour Crater, January 22, 2015.

Opportunity's traverse up to February 2015 as it approached Spirit of Saint Louis Crater and Marathon Valley, and came close to traveling the distance of a traditional marathon (about 26 miles or 42 km)

In October 2016 the ESA's Schiaparelli lander attempted to re-use the proven Meridiani Planum landing site, with a landing ellipse that kisses the Endeavour crater location where Opportunity is still functioning.[47] This allowed the opportunity for Opportunity to attempt to image the lander during its descent from the surface of Mars.[48] Contact was lost during descent

MRO Context Camera images of Schiaparelli landing site; before (29 May 2016) and after (20 October 2016). The large black spot indicates the impact by the lander, and the white spot its parachute.[49]

Two of the seven final landing candidates for MSL were relatively near to Endeavour, one was in Miyamoto (crater) and another was south of Endeavour in southerner Meridiani.[50]Gale (crater) won the selection

Endeavour crater can be see on the right side of this map about halfway down;in the bottom left is the proposed landing ellipse for MSL in Miyamoto crater.

MER-B from 2011 to 2016 explored the Western rim of Endeavour, starting at Cape York (Mars) then moving down through Botany Bay to Solander Point, along Murray Ridge moving south to Marathon Valley; in late 2016 it began moving inward to the crater floor: It then moved back to the rim and went south to gully named Perseverance Valley, leaving the Cape Tribulation section, and heading towards Cape Bryon.

A detailed-class rover traverse map by the mission, released on September 28, 2016 showing the track of the rover up to Sol 4500 as it heads deeper in Endeavor crater

Opportunity looks at the southern end of Cape Tribulation as it heads south, showing how the Western rim ridge[52]

In March 2016, while trying to reach target on the slop of Marathon Valley in Cape Tribulation, the Mars rover attained a slope of 32 degrees, the highest angle yet for the rover since its mission began. This was so steep that dust that had accumulated on its top panels began to flow downward.[53]

This crater sits at the Western mouth of Marathon Valley, south Cape Tribulation on the western rim of Endeavor crater. It was visited by the MER-B Opportunity rover in May 2015.[54]

In May 2015 the rover visited what was dubbed Spirit of St. Louis Crater, a shallow crater about 110 feet (34 meters) long and 80 feet (24 meters) across. In its center is Lindbergh Mound, about 2-3 meters (yards) high. This version of the panorama is annotated and in false color[54]

The proposed landing ellipse in Miyamoto when it was one of seven finalists under consideration as a landing site for MSL.[50] Endeavour crater can be seen on the right side of the map, the top of three medium-sized craters in a north-south line. This map is color-coded based on elevation.

Map showing the location of Endeavour Crater and other, nearby features